Dust
by FlamingFlyingFoxOfDoom
Summary: Edward found a blue jacket.
1. Chapter 1

The rain came down gently, its drops pittering and pattering against the leaves of the surrounding trees. Roy snorted, his hands deep in his pockets as his Lieutenant adjusted the umbrella she was holding.

The other men of his group were strewn about, doing miscellaneous jobs in preparation for the larger one at hand. Before them, the mouth of a large cave opened up, decorated with sprawling vines and stray patches of moss.

The only reason he and his team were called in was because it seemed like the cave was inhabited. The military sent down several spelunkers, all of which had come back completely terrified at the claim of encountering monsters. The claw and bite marks on them seemed to be plenty of proof.

So not only was there a potential civilization, but they were dangerous.

Really, Roy wasn't too worried overall. It was raining outside, but inside the cave should be nice and dry. There was only one little problem….

"So are we gonna just stare at it all day or are we going in?" Edward demanded, shoulders hunched and arms crossed. A keen eye can see him tremble slightly due to the cold, but the stubborn boy would refuse to let it show that it's bothering him.

Roy sighed, pinching the bridge of his nose "In a little bit, FullMetal."

Edward and Alphonse he could deal with. Just Edward was a bit more difficult. Whatever was down there, the military wanted to keep it confidential, so Alphonse was forbidden to join the expedition. So now he was stuck with a pouty, reckless, rude, punk-ass-

Ahm.

Roy was stuck with Ed.

After several more minutes of little preparations, the group eventually headed in.

"Keep your eyes peeled." Roy said over his shoulder. His soldiers nodded, and even Ed gave a short grunt of acknowledgement as he glared about. Roy smirked and turned his gaze back forward.

Say what you will about Edward, but he was no idiot.

The group travelled in relative silence, studying their surroundings intently, looking for any signs of sentient life. They found some quickly. Not too long into their walk they came across what appeared to be a throne room. Yellow flowers littered the ground around a single standing throne, and a cape and what appeared to be a trident stood vigil over a large mound of dust.

Roy studied it skeptically, running his fingers along the engravings of the trident.

"Looks ceremonial." Roy hummed, noting the flower carved into the end of the shaft.

"Perhaps it is." Riza said with a slight tilt of her head.

While the two muttered to one another about the purpose of the cape and what the dust may have been, Edward's attention drifted to the entrance of the room. A frown creased his face and he heard…..something.

"Hey." the boy interrupted Roy and Riza's chat. They both turned to look at him. "I think I hear something from the other room."

Roy nodded, pulling his glove on tighter. "All right. Let's go."

With a nod, the group set off, Roy in the lead. As they moved forward they all caught the noise. It sounded something like claws on marble. One of the monsters, perhaps?

They went down a short hall, and soon found themselves in a much larger hall. Tall columns stood guard, set in rows on either wall. The hall itself seemed to be made of gold, dimly reflecting yellow. The sound of rain was distant.

Ed looked around briefly, and a flicker of movement caught his eye. The sound of claws moving echoed down the hall and the brief flicker of something yellow disappeared around the corner at the end.

"Hey!" Ed yelled, breaking into a run "Get back here!"

"FullMetal-!" Roy snapped after a moment's surprise "Where the hell are you going-!?"

Ed yelled back at him "I saw someone run off, so I'm chasing them d-AH!" Ed's sentence was interrupted as his foot caught on something that was lying on the ground. Whatever it was, it had slid backwards as his foot made impact with it and the rest of him plummeted to the floor, landing face-first in a pile of white dust.

Ed threw himself out of it, coughing up the pesky stuff while at the same time trying to wipe it off his face. Riza had approached him while he fell, and was now helping him up.

"Thanks." He muttered.

"Of course." Riza said with a nod. Roy stood behind her, his eyes locked down the hall.

"You said you saw someone?" he said. Ed nodded, shaking off his coat.

"I definitely saw _something_ move." He said. Roy frowned, giving a quick motion to the rest of his group. They all gave a stiff nod, holding their guns at the ready.

"Let's keep going, then." Roy commanded. They all gave a quiet 'sir' (except for Ed) and approached slowly.

No matter how lightly they stepped, it seemed as if their footfalls would echo off the walls, coming back to them twisted and mangled. What should've been a quick stroll seemed to drag on as they all waited in apprehension for whatever Ed saw to appear again. The sound of rain grew louder.

The group exited the hall, finding themselves in a narrowed, less glamorous one. A pair of metal doors was to their right, and a little further down there was an overlook of a city of sorts. As they all took a moment to examine it, Roy made an observation.

"People definitely live down here."

"No shit." Ed snorted, glaring up at him "What makes you think that?"

Roy gave him a look that was a cross between a glare and pure annoyance.

"Alright, enough of that." Riza interjected. She glanced around "Perhaps there's a way down from here?"

"Might be." Roy said with a frown.

"Should we look?" Havoc asked, smothering the ember on his cigarette on the bottom of his boot.

Roy nodded "Keep your guard up."

They all gave a 'yessir' and began to search the area.

Ed glanced about, still trying to get all of the dust off of his face. Frowning a bit, he looked over his shoulder at the way he came.

"Colonel, I'm going to go back." he said.

"Getting cold feet, FullMetal?" Roy said without even looking at him. Ed snorted, whipping his gaze around angrily.

"Not back outside!" He snapped "I just mean back to that hallway!"

Roy eyed him a moment, then gave a nod "Yell if you see anything."

"Right." Ed mumbled, turning on heel and storming off.

His anger was quickly forgotten, however, as he re-entered the hall. He knelt by the pile of dust he had fell in and picked up what had made him slip. Ed shook some dust off of it and gave a tilt of his head. "A jacket?"

Ed blinked his yellow eyes, turning his attention to what was underneath the jacket. A dark red streak was smeared into the dust. Curious, Ed discarded the coat to the side and laid on the floor to get a closer look at it. With a quick sniff, he caught the whiff of….something. Kind of reminded him of food. Hamburgers, to be exact.

"Ketchup?" He blinked, brow furrowing as he tried to puzzle together what it could mean. Ed gave a quick shake of his head, getting to his feet and making his way further down the hall. He was beginning to think the piles of dust were a bit more than that, although he couldn't come to any conclusion as to what they were… So for now, he'd investigate the first pile they came across and-

STEP STEP STEP STEP STEP

Someone was running towards him. Ed turned, expecting to see Havoc or one of the others. But imagine his shock when he saw a child running towards him.

With a psychotic grin.

And a knife.

Ed yelped, twisting to the side as the knife swung down in an arch.

"What the hell-!?" He snapped, dodging another swipe of the knife. "Kid, what are you DOING here-" he ducked under the blade "AND WHY THE FUCK ARE YOU TRYING TO KILL ME!?"

* * *

 **A/N**

 **I know what you're thinking.**

' **Hey dont you already HAVE a FMA-Undertale crossover?"**

 **Yes, Yes I do.**


	2. Chapter 2

The knife was swung again, gliding through the air to cut up at his throat. Ed quickly dodged, stepping back to put some distance between himself and the child.

"What are you doing!?" He demanded, skidding in a semi-circle so he was behind the murderous brat. He clapped his hands, throwing them down to the tiled floor. Ground shot up around the child, entrapping them in a cage.

Ed straightened himself out, dusting off his pants. Through the corner of his eye he saw the glint of the knife. Startled, he flailed backwards. The child was in front of him, swerving quickly to dive into another attack.

"How the hell-" Ed exclaimed, putting more distance between them.

Suddenly it seemed his body moved on its own. His arm shot up, palm pointing in the child's direction. A surge of blue flared from his left eye, bones solidifying and jutting quickly out of the ground. The child dodged them all, weaving in between them like a snake. They jumped into the air, red eyes gleaming and knife pointing downwards.

Ed's body moved again, suddenly behind the child's back, watching as they stabbed into the floor.

His arm swept out in front of him and the air trembled. A monstrous skull spun into existence, its mouth open wide as a white fire blaze within its jaws. The child couldn't avoid that blast, and they were burnt beyond recognition.

The smell of smoldering flesh and the screams of the child broke whatever force was moving Edward. He rushed towards them, his heart feeling as if it were beating in his throat.

"Kid-"

They suddenly turned and heaved their knife down in a final strike, tearing through his coat, his shirt, his flesh. Blood gushed from the cut, coating the child's knife and splattering against their face.

Everything shattered.

Ed dropped to his knees, breathing heavily and clutching his chest tightly. His chest heaved, vomit and blood being thrown from his mouth. Sweat slicked his face, his body trembling.

Shaking, he looked up. But no one was there.

He looked down the hall.

But no one was there.

He looked for the cut.

But nothing was there.

"What the hell….?" Ed croaked, pressing the palm of his flesh hand to his chest. He felt no sting of a wound there. He felt no blood. He stared, mouth twisting into a frown. His eyes narrowed and he forced himself to get to his feet. Something drew his gaze to the blue jacket.

He gingerly stepped over to it as if he were approaching a wild animal. Still shaking, he picked up the jacket and stared at it. A feeling of dread loomed over him.

"Edward?" someone said. Ed looked up to see Hawkeye frowning at him. At seeing the blood on his mouth, her eyes widened and she ran forward. "Edward, what happened?"

Ed didn't respond right away, staring at her. After a moment he numbly replied "I don't know."

Riza frowned "What?"

Ed shook his head, tilting his gaze back to the jacket. It felt heavy in his hands. On impulse, he reached into the coat's pocket and pulled out a what seemed to be a photograph smeared in dust. He draped the jacket over the crook of his right arm and licked his thumb, wiping the photograph clean.

Two skeleton grinned back at him from the picture. One taller and wearing what seemed to be a chest plate and a scarf, the other shorter and wearing …. A blue jacket. He absent-mindedly ran his thumb over the photo, his eyes focused on something far away.

Riza watched him do this, her gaze softening in concern. She placed a hand on the boy's shoulder.

"Edward, what happened?"

Ed shrugged her hand off, pocketing the photo. "I just got a bit sick. Happens sometimes when it rains."

Riza didn't seem convinced "Perhaps you should go home?"

"Nah." Ed dismissed her with a lazy wave, walking past her "Let's get back to the others."

Riza didn't say anything, simply following him while staring into the back of his head.

The two rejoined the rest of the group. Roy, who was talking something over with Havoc, turned to look at them as they approached. His eyes caught on the jacket Edward was carrying and he frowned.

"Find something, FullMetal?"

Ed nodded, holding the jacket out for the group to see "I noticed something. With the dust in the throne room in the pile in the hall there, there's always some sort of clothing."

Roy raised an eyebrow at that. He crossed his arms over his chest, his eyes closed. "That does seem to be the case…." His gaze was sharp when his eyes opened "Let's go further in. Maybe there's more to this than a lazy housekeeper."

The group nodded as one, following Roy as he lead the way down the hall. They quickly came across another pair of metal doors. Roy motioned to his men, who all tensed, guns at the ready. He clicked a button or two just to see what would happened and the doors opened.

"An elevator." Ed observed "There was another one back there too."

"Must be how whatever lives down here gets around." Roy said. He looked around inside briefly. "There's not enough room for all of us in here." He frowned in thought. "And there's more than one of these. They must lead to different places, right?"

"So how about we split up and look through all of them?" Ed suggested. Roy shook his head.

"That would be stupid." The Colonel said. At Edward's scowl, Roy held up his hand to signify he wasn't done talking "Everyone who's been down here says there are hostile creatures here. If they decide to attack in a horde and we're split, we're likely to be outnumbered. So we're going to avoid that."

"So what's the plan?" Ed muttered.

Roy thought. "Let's look in the others and see if they're larger. If not, we'll have to split into groups to make it through. But the first group will stay near the elevator and wait for the second."

They all nodded their understanding. After a brief inspection, they found that that would have to be the plan. Edward, Roy and Riza were the first group. If there was an ambush waiting for them, Roy calculated that the three of them would be an efficient first wave as they waited for the others. The three stood in silence as the elevator hummed its way down.

Roy's gaze darted to Edward, who was still holding the jacket he had found. Almost clinging onto it if one took a close look at the boy's tight grip on it. And the smear of red on Ed's lips didn't go unnoticed either. The Colonel exchanged a look with his Lieutenant, who had also been looking at the young soldier. The two didn't know what to think. Ed seemed fine, physically. But something was clearly on the alchemist's mind.

Ed didn't offer anything, so the two let it be for the moment.

The elevator stopped, the three got out. And instantly were electrocuted. Ed, having two metal limbs, had the most severe reaction to the shock, his body spasming as he crumpled to the ground. Riza let out a short shriek, but bit her lip and managed to keep standing. Roy instantly snapped his fingers, setting the surrounding area ablaze.

The electricity short-circuited, sputtering out and a soft, startled squeak was heard. Riza moved to stand in front of Edward, gun aimed steady despite her shaking breaths. Roy kept his composure, fingers poised to snap again.

A short, yellow lizard-like creature stood some distance away. They were shaking, legs spread and hands holding up a gun of its own. Sweat beaded against its scales.

"G-go away!" it stammered.

Roy took a step forward. "Relax or we'll have to get violent."

The lizard cracked a forced, nervous grin "S-seems like an o-oxymoron there, h-huh?"

Roy smirked "I suppose." His smirked quickly dissipated "I have some questions I need answered."

The lizard seemed hesitant to respond. It shakily lowered its weapon "J-just questions-? OH MY GOSH." It dropped all wariness, darting past Roy. The Colonel, actually startled by the sudden motion, took a moment to respond.

Riza didn't.

A bullet skimmed the side of the lizard's face, bringing blood swelling to the surface. It squeaked, backing off a bit. Tears were shimmering in its eyes, but it spoke anyway.

"A-are they alright?" It asked, clearly referring to Edward. The boy was on the ground still, breathing hard.

"You just electrocuted us and you're asking that?" Roy hissed. The lizard shuffled its feet, wringing its tail.

"W-w-well, yeah. B-b-but it was j-just supposed t-to stun y-you, n-n-not hurt you this bad-!" It stammered. "L-let me help them!"

"Like we're just going to trust you with that-!" Roy snapped.

"It's fine!" Ed hollered over him, pushing himself up from the ground. His yellow eyes showed no concern. "Yeah, I could use the help. That really….shocked, me. Heh."

Roy and Riza stared at him.

"FullMetal, what the fuck?"


	3. Chapter 3

He had no clue what was going on. He just knew he ached all over, Alphys was alive and the world was still going.

He raised the fleshy left arm, placing the fingertips gently on the metal shoulder of the right. There was a faint ringing in his foreign ears.

Alphys was sweating nervously, trying to not look at the group of humans that had her surrounded, pinned underneath their wary glares. Four more humans had joined with the two he had woken up to, and they all have insisted that Alphys kept him near them. His jacket lay across his lap, flecks of his dust still clinging onto it.

"O-okay, that s-should do it." Alphys stammered, straightening her glasses. She took a few cautious steps back, ducking her head to avoid the eyes trained on her. "He s-should be f-feeling a lot b-better now."

A blonde human stepped forward, kneeling down to be eye-level with him.

"How do you feel, Edward?" she asked kindly, her eyes soft.

Sans put together that must be the name of whoever's body he was in. He opened his mouth to reply that he wasn't the human she thought was inhabiting the body, but he ended up biting his new tongue by mistake.

"Ow." He muttered, covering his mouth with the fleshy hand.

The group of humans seemed placated by this response.

"Great, now get up." The black-haired man said, turning to look towards Alphys instead. "And I've got some questions for you, if you care to answer."

Alphys grinned nervously "D-d-do I have a choice?"

"Not particularly." The human said.

Sans's eyes narrowed into a glare. His eyes sparked blue for a brief second, training onto the Human Leader. He pushed himself up, forcing down his unease and put himself between Alphys and the black-haired human, abandoning his jacket.

"Hey, no need to be so hostile." He said with a shrug. "She doesn't seem all that dangerous-"

"You seem to forget it-"

"She."

"….Fine, you seem to forget _she_ electrocuted you."

So that explains the achy feeling, at least.

Sans shrugged, turning his back to the humans and turning his eyes on Alphys. He made a brief motion with his hands, a type of sign language only the two of them knew. Alphys's eyes widened.

"Sans!?" She exclaimed.

Sans shot her a pointed glare as the rest of the humans looked on in confusion. Alphys slapped her hands over her mouth, eyes darting about behind her glasses as sweat slicked down her scales.

"Why did you just yell that?" The human leader said with a glare.

Sans shrugged, turning on heel. For show, he let his left eyes blaze blue. The other eye, much to the fear of the humans, turned completely white.

""Cause _I'm_ Sans." He said, noting how his borrowed voice echoed with his original voice.

The humans all tensed up, with the leader being the exception. He took a step forward as Sans dismissed his magic, standing tall over Sans. This didn't unnerve the former skeleton in the slightest (he was around the same height as he was before so he was used to having to look up at people). Alphys squeaked behind him, grabbing his arm as if to pull him back.

"Don't worry, Al." Sans said quietly, looking over his shoulder. His attention was drawn back to the leader when he spoke.

"So, Sans." He said, eerily calm. Sans gave him a lazy grin which quickly turned into a startled gasp when he was hauled up from his collar. His face was only an inch away from the human's, and his eyes were….frightening, to say the least. The human growled at him "What did you do to Edward?"

Sans's grin returned when he replied with a shrug.

"No clue. Must've passed out when Al electrocuted him." He said.

" 'Al'?" the human repeated, quirking an eyebrow.

Sans jerked a thumb over to Alphys "Alphys."

"H-hi." Alphys stammered, giving a timid wave.

The human's glare moved over to her, his anger blazing in his eyes. Sans decided to fix this by booping him on the nose.

"Ey, I'm right here." Sans said.

The human leader dropped him, storming over to Alphys.

"What did you do to him?" He said in a façade of calm.

"N-nothing!" Alphys squeaked. Sans was quickly in between them again.

"Yeah pal, Alphys got nothin' to do with this." Sans said, rocking on his heels. He thought a moment, eyeing his discarded jacket. Sans lifted a hand, curling a finger towards himself and his jacket flew towards him. Sans ignored the confused and baffled looks the humans gave and grinned up at the Leader. "Did Ed pick up this thing for a reason?"

The human continued to glare at him.

"Geesh, not much for conversation, huh?" Sans shrugged "Okay, I'll stop peakin' 'round the bush. There was probably a pile of dust or somethin' round this. Did Ed do something with it?"

The female spoke up this time "He fell in it."

Sans hummed "Fell in it? Did he, like, eat any of it?"

"He was coughing it up, so he might have accidentally swallowed some." The leader said. He tilted his head "Why?"

"Well, ya see, that dust was what was left of my body." Sans chirped nonchalantly.

…

"Okay, that makes no sense." The leader pouted "If someone eats someone's body or whatever, they don't gain their consciousness or anything."

"Do ya speak from experience?" Sans grinned.

The leader glared again.

"Geesh, don't like jokes either?" Sans muttered "Yer kinda boring."

The leader shook his head, muttering something "Okay, so what happened? How is that possible? I want answers." He poised his fingers as if he were about to snap his fingers "Now."

Sans's grin didn't falter as he tilted his head "….Or what? Yer gonna smooth jazz us to death?"

Alphys squeaked "S-sans, no! He- uh- when he snaps, he can make fire, somehow…."

Sans's grin turned a bit stiff "Ah. Got it. Um. Okay, listen, I ain't good at the whole explaining thing, but I'll try my best." He took a step towards Alphys, making a point to hide most of her body with his borrowed one. "But, uh, no hurting my pal here."

"We'll see." The leader said "Explain."

Sans chuckled awkwardly "Right, it'll be a bit hard to explain to humans, but, uh, I'll try."

"Monsters are made out of magic, right? And that magic comes from the SOUL of the monster. When a monster dies, the magic holding their body together falls apart and they turn to dust. That dust can hold fragments of a monster's SOUL. When, uh, your friend here faceplanted in my dust, he must've, uh, well, ingested some of it. When that happened, the fragments of my SOUL left in the dust must've reformed to….actually, hold on, I can CHECK this."

Sans placed his flesh hand to his heart, his jacket hanging from the crook of his arm. He took a breath, moving his hand away from his chest, guiding what looked like a heart out of it.

The humans stared.

"What the hell is that?" The leader asked.

Sans grinned "A SOUL. Y'think I was making shit up?"

"A little bit, yeah." The human leader said.

"At least yer honest." Sans grinned. "Anyway, let's take a look see….. yeah, I think I see the problem."

The heart he had guided out, the SOUL, was red. In the middle, pulsing faintly, was a small white, upside-down, heart.

"See this part?" Sans said, pointing to the white heart. "This here is what's left of my SOUL."

"….So Edward somehow absorbed it?" The leader said slowly, crossing his arms "Is that what you're saying?"

"Eeyup." Sans grinned, pushing the combined SOULs back into his borrowed body.

"B-b-b-ut that still doesn't make sense!" Alphys stammered. Her eyes darted over to the humans and she hastily explained "I mean, when a monster d-dies, we usually spread the dust on something that monster liked in life. B-but that doesn't mean that the object gains the monster's consciousness."

"Usually, yeh." Sans said "But, this situation is a tad different. Did you notice the SOUL this kid has?"

Alphys thought a moment. Then her already pale face turned a bit paler "Determination."

Sans nodded, his grin finally dropping "Yeah. Determination."

The humans looked amongst themselves. The human leader spoke up again.

"So, Edward is okay?"

"Yeah." Sans said with a nod "He'll probably regain control when he wakes up. Y'probably can't tell, cause your humans and all, but his SOUL is sleeping."

The leader gave a slow nod. "Well, I suppose we have no choice but to believe you for now."

"Cool." Sans grinned again, giving a thumbs up "So can we have some names now? Kind feel stupid referrin' to ya by just traits I notice."

…

"Okay?" The leader said again. He turned and introduced all of them in turn. They each gave an awkward greeting in return.

"So, Edward _is_ okay, right?" Fuery asked.

Sans gave another nod "His SOULs intact and all, so ….. yeh, he's fine."

Roy hummed "I have a lot more questions about SOULs and magic and all that. So, Sans, while we have you here, you're going to be answering our questions."

Sans whined "I don't wannnaaaaaaa." He plopped onto the ground, leaving Alphys to squeak in fear. At the noise, Sans quickly scrambled back to his feet, allowing the yellow monster to hide behind him again.

"So all that dust was….monster corpses?" Havoc frowned, his cigarette drooping.

Sans nodded again "Yeh."

Alphys fidgeted behind him, her eyes misting over.

"…Why so much of it?" Roy demanded. Alphys choked, turning her back on them and hiding her head in her hands.

Sans's grin turned unnaturally tight. His eyes went white "Well, let's just say some humans jump straight to murderin' everything they don't like."

Roy frowned, exchanging a look with Riza. She spoke slowly.

"I see. Well, if you do not mind, we still have some questions we need answered. Then we'll leave."

Sans chuckled a bit "Yer a bit nicer than Roy-boy." He shrugged "Although, I've kind of been…dead, so I don't really know what's been going on." With this, he looked at Alphys. She sighed, wiping at her eyes and fidgeting with her tail.

"Y-yeah…. I'll explain."


End file.
